engleski

Response to neoadjuvant chemotherapy according to the triple-negative breast cancer subype

Neoadjuvant chemotherapy (NAC) is used as a systematic pre-surgery approach to treat locally advanced or inoperable breast cancer. Following NAC, pathologists estimate the response to treatment based on tumor size and cellularity, number of positive axillary nodes, and largest metastatic deposits using a residual cancer burden (RCB) calculator (MDAnderson Cancer Center RCB online calculator). The calculated RCB classes include pathological complete response (pCR) without residual cancer (RCB-0), minimal residual disease (RCB-I), partial response (RCB-II), or extensive residual cancer (RCB-III). The paper presents retrospectively collected data on triple-negative breast cancers (TNBC) surgically treated after NAC, which had an estimated response to therapy defined through the RCB class, and determined the expression status of AR (androgen receptor), CK5/14 (basal keratin 5 and 14) and PD- L1 (Programmed death-ligand 1). Based on the expression CK5/14, we classified TNBC into basal- like and nonbasal-like subtypes and assessed the effect of NAC according to the basal type and PD-L1. Complete pathological response (pCR, RCB-0) was achieved in 26 cases (31%), minimal residual disease RCB-I was found in four cases (4.8%) while 54 patients had poor response to NAC, 34 (40.4%) with RCB-II and 20 (23.8%) with RCB-III. Thirty-eight TNBC cases (45.2%) were of the basal-like subtype while 46 were of nonbasal-like subtype (54.8%). The median expression of Ki-67 proliferation marker on core-needle biopsy samples in tumors that achieved pCR was 80% and for RCB-I 70%, while tumors with Ki-67 lower than 60% had a poorer response. We observed almost equal distribution of RCB scores within basal-like and nonbasal-like subtypes (χ2 =0.003, P=0.974). Taking into account only the expression of AR (positive in 26 cases), we found that 41.4% of AR-negatives had a better response to NAC (pCR and RCB-I) compared to 23.1% of AR-positive cases, but not statistically significant (χ2 =1.88, P=0.170). In the group of nonbasal-like TNBCs, AR was negative in 62.5% of cases, and there was also no difference in RCB based on positive or negative status of AR. Furthermore, we found that patients with PD-L1 positive status had better response to NAC (Fisher Exact test P=0.031), but we had only 36 such cases. PDL1 was positive in 6/15 cases that achieved a good response to NAC (pCR or RCB-I) from the nonbasal- like group, and in 4/6 cases from the basal-like group that also achieved a good response. According to our results, the response to NAC does not depend on the basal subtype of TNBC. A small group of subjects and the need for longer monitoring of treatment outcomes should certainly be taken into account, in order to fully confirm the results obtained.

triple-negative breast cancer, neoadjuvant chemotherapy response, residual cancer burden, basal-like subtype

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